Given a web handler in some arbitrary MonadSnap monad, a function
specifying how to evaluate it within the context of the test monad, and a
RequestBuilder defining a test request, runs the handler, producing an
HTTP Response.

Given a web handler in some arbitrary MonadSnap monad, a function
specifying how to evaluate it within the context of the test monad, and a
RequestBuilder defining a test request, runs the handler, returning the
monadic value it produces.

Sets the request's query string to be the raw bytestring provided,
without any escaping or other interpretation. Most users should instead
choose the setQueryString function, which takes a parameter mapping.